We have found out a strange
feature from OCS with expanded environment. When we have NLB in use,
users are able to login using what ever signin names they like, as long
as they are enabled OCS users. We have Cisco's NLB in use. So I'm able to use my colleague SIP login and they are able to use my, without user ID and passwords.
If we skip the NLB there are no problem like this.